JPS6216523Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a worm rack of a hydrostatic bearing type.

Worms are used as one of the feeding mechanisms of various machines.
Racks are used, and some have a feed speed of 10 m/min or more. Hydrostatic bearings are used on the tooth surfaces in order to lubricate the meshing surfaces and reduce sliding resistance to ensure smooth operation as the feed rate increases.

The worm rack of the conventional hydrostatic bearing system is the first
It is shown in Figs. A worm hub 1 is rotatably mounted on a shaft 2, which shaft 2 has a longitudinal bore 5, 6 which is connected to a lubricating oil distributor 3, 4, respectively. The shaft 2 has grooves 7, which extend in the circumferential direction of the outer circumferential surface of the shaft 2 and are offset from each other in the axial direction.
8 are provided, and the grooves 7, 8 are connected to the vertical holes 5, 6, respectively.
communicate with. A plurality of distribution passages 9 and 10 are alternately located in the worm boss 1 and distributed in the circumferential direction and parallel to the axis. The distribution passage 9 is connected to the one groove 7.
A hole 1 having a connecting hole 11 that opens toward the range of , and communicating with the right side surface of the worm tooth 12 in the figure.
It has 3. On the other hand, the distribution passage 10 has a connecting hole 14 that opens toward the range of the other groove 8 and also has a hole 15 that communicates with the left side surface of the worm tooth 12 in the drawing. As shown in FIG. 2, the grooves 7 and 8 are
Since it extends only in the circumferential direction where the worm teeth 12 and the racks 16 engage, lubricating oil is supplied only from the connecting holes 11 or 14 which correspond to these grooves 7, 8 at each time. Therefore, it is supplied only to the meshing portion between the worm tooth 12 and the rack 16. Note that 17 is easy 16
The lubricating grooves 18 and 19 carved in the grooves 18 and 19 are ring grooves and recovery passages for recovering the lubricating oil supplied to the sliding surface between the shaft 2 and the worm boss 1 from the grooves 7 and 8, respectively.

In addition, there are other hydrostatic bearing type worm racks as shown in Figures 4 and 5. Fuel filler port 2
Low pressure oil and static pressure oil for extruding bubbles are supplied from 1 and 22, respectively. The lubricating oil is distributed through the distribution passages 23 and 24.
It is sent to the part where the worm teeth 25 and the rack 26 engage. At this time, in FIG. 5, static pressure oil is supplied from the distribution passage 24 corresponding to the position where the worm teeth 25 and the rack 26 engage, and from the distribution passage 23 near the position where the worm teeth 25 and the rack 26 engage, the oil is supplied to prevent air from entering the engagement part. Low-pressure oil is supplied for this purpose, and no lubricating oil is supplied from the distribution passage 27 in the portion that does not mesh.

However, the former method is complicated because it has a structure in which lubricating oil is supplied to both sides of the teeth through two independent pipes. Further, in the latter case as well, since the structure includes separate circuits for supplying static pressure oil and low pressure oil for preventing air entrainment, the structure is complicated and increases costs.

The present invention eliminates these drawbacks and provides a low-cost, high-rigidity, high-efficiency hydrostatic bearing type worm rack. The structure of the present invention that achieves such an object is such that, in a worm rack that is composed of a worm that is slidably rotatable on the outer circumferential surface of a fixed shaft and a rack that engages with the worm, there is a position where the worm and the rack engage. The outer circumferential surface of the fixed shaft at is a large notch that ensures the required flow rate of oil, and the worm extends from the large notch toward the outer circumferential surface of the fixed shaft at the center of the position where the worm and the rack do not engage. A notch portion having a small notch portion whose gap gradually becomes approximately zero is provided on the outer circumferential surface of the fixed shaft, and a flow path communicating with the notch portion is provided on the fixed shaft. It is characterized in that a plurality of distribution channels are provided up to the inner circumferential surface that can communicate with the notch.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in the drawings.

A large amount of lubricating oil is supplied to the part where the worm and the lug engage, and a small amount of lubricating oil is supplied near the engaging part to prevent air from entering the engaging part.
It is rational not to supply to parts that do not mesh. The present invention satisfies these requirements with only one pipe.

One embodiment is shown in FIGS. 6 and 7. A worm gear box 31 is fixed to a bed (not shown). An oil supply shaft 32 as a fixed shaft is fixed to the worm gear box 31. A worm 37 is provided in the worm gear box 31 via bearings 34, 35, and 36 so as to be able to slide and rotate on the outer peripheral surface 33 of the oil supply shaft 32. Note 5
5 is an O-ring. The worm 37 is rotated by a motor or the like (not shown) via a gear or a belt. The worm 37 is engaged with a rack 38 that is integrated with a base 39 that is movable left and right at the bottom in the figure. A notch 40 is provided on the outer circumferential surface 33 of the oil supply shaft 32. The notch 40 is a large notch 40 that ensures the required flow rate of lubricating oil at a position on the circumference (lower in the figure) corresponding to the position where the worm 37 and the rack 38 engage.
a is provided. Further, the cutout portion 40 is provided with a portion 40b at a position where the worm 37 and the rack 38 do not engage with each other, and the oil supply shaft 32 has a substantially zero gap with the worm 37. In order to supply a small amount of lubricating oil near the meshing portion, both ends of the large notch 40a in the circumferential direction are located at portions 40.
A small notch 40c is formed whose distance from the worm 37 gradually becomes approximately zero toward the direction b. The size of this large notch 40a is determined by the size of the teeth 45 of the rack 38.
The angle α formed by both ends of the large notch 40a extending in the circumferential direction is determined by the size of the pocket parts 41 and 42 provided in the pocket part 41 and 42, and the angle α formed by both ends of the large notch part 40a extending in the circumferential direction is made slightly smaller than the angle formed by both ends of the pocket part 41 or 42. .
The oil supply shaft 32 has this large notch 40a.
A flow path 43 communicating with is formed. The flow path 43 passes through the axis of the oil supply shaft 32 and is connected to a pump unit (not shown). In order to feed lubricating oil from the large notch 40a to the teeth 46 of the worm 37, the large notch 40 is
A plurality of distribution channels are provided up to the inner circumferential surface 44 that can communicate with a. The distribution flow path in this embodiment is as follows. A donut-shaped valve plate 48 is fixed to the worm 37.
Four radial main flow passages 47 are bored to the inner circumferential surface 44 of the worm 37 at intervals of 8 to 90 degrees. It is preferable that at least one main flow path 47 is always located within the range of the pocket portion 41 or 42.
From each main channel 47, two branch channels 49 and 50 are bored extending from the valve plate 48 to the worm 37 in parallel to the axis of the worm 37.
a branch channel 49 located within the valve plate 48;
50 is provided with throttle valves 51 and 52, respectively, in this embodiment, making it possible to adjust the flow rate of lubricating oil.
From the branch channels 49 and 50, the pocket portions 4
Supply holes 53 and 54 are connected to the right and left side surfaces of the teeth 46 that are opposite to the teeth 2 and 41, respectively.

In this embodiment, the number of main channels in the distribution channel is four, but the number is not limited to four and may be determined as necessary. Furthermore, although the notch is provided on the outer circumferential surface of the fixed shaft corresponding to the position where the worm and the rack engage, it is only necessary to supply a large amount of lubricating oil to the engaging part, and therefore the cut in the circumferential direction is sufficient. In addition to changing the position of the notch, the opening position of the distribution flow path in the circumferential direction on the inner circumferential surface of the worm may be changed accordingly. Also,
A hole or a groove may be provided as the notch.

The action of the worm rack of such a hydrostatic bearing system will be explained.

The worm 37 rotates and lubricating oil is supplied from the flow path 43 to the notch 40 . At this time, in FIG. 7, lubricating oil is not supplied to the upper main flow path 47, but only a small amount is supplied to the left and right main flow paths 47.
That is, the main flow path 47 in the upper part is connected to the worm 37.
The lubricating oil is not supplied to the parts 40b where the gap is approximately zero, and the small notches 4 are provided in the left and right main flow passages 47.
0c are facing each other and a small amount of lubricating oil flows. Further, a large amount of lubricating oil flows into the lower main flow path 47 because it directly communicates with the large notch 40a. Therefore, as the teeth 46 of the worm 37 approach the engaged position from the non-engaged position, lubricating oil is gradually supplied and the air in the branch channels 49, 50 and the supply holes 53, 54 is expelled. When the teeth 46 reach the meshing portion, a large amount of lubricating oil is supplied from the supply holes 53 and 54 to the pockets 42 and 41. The amount of oil supplied to the pockets 41, 42 can be adjusted by throttle valves 52, 51.

As described above with reference to the drawings, according to the present invention, the fixed shaft is provided with a notch consisting of two parts, one for small quantity supply and one for large quantity supply. Automatically performs three actions: lubrication is not applied to non-meshing areas by simply providing a path, a small amount of lubrication is applied near the meshing areas, just enough to expel the trapped air, and a large amount of lubrication is applied to the meshing areas. Can be done. Furthermore, since it is equipped with a throttle valve, the amount of lubricating oil supplied can be freely adjusted, and it is possible to maintain smooth operation by reducing the lubrication and sliding resistance of the meshing surfaces.

[Brief explanation of the drawing]

Figures 1 to 3 relate to a conventional hydrostatic bearing type worm rack; Figure 1 is a sectional view, Figure 2 is a sectional view taken along line A-A in Figure 1, and Figure 3 is an explanation of the hydraulic unit. 4 and 5 relate to other conventional hydrostatic bearing type worm racks, in which FIG. 4 is a sectional view, FIG. 5 is a BB sectional view of FIG. 4, FIG. 7 shows a worm rack of a hydrostatic bearing type according to the present invention, FIG. 6 is a cross-sectional view, and FIG. 7 is a cross-sectional view taken along the line CC in FIG. 6. In the drawing, 31 is a worm gear box, 32 is an oil supply shaft, 33 is an outer circumferential surface, 34, 35, and 36 are bearings, 37 is a worm, 38 is a rack, 39 is a base, 40 is a notch, and 41, 42 are pockets. 43 is a flow path, 44 is an inner peripheral surface, 45 and 46 are teeth, 47 is a main flow path, 48 is a valve plate, 4
9, 50 are branch flow paths, 51, 52 are throttle valves, 5
3 and 54 are supply holes, and 55 is an O-ring.

Claims (1)

[Scope of utility model registration request] In a worm rack consisting of a worm that is slidably provided on the outer circumferential surface of a fixed shaft and a rack that engages with the worm, the outer circumferential surface of the fixed shaft at the position where the worm and the rack engage are arranged such that the required flow rate of oil is a small notch in which the gap with the worm gradually becomes substantially zero from the large notch toward the outer peripheral surface of the fixed shaft at the center of the position where the worm and the rack do not engage; A notch portion having a diameter is provided on the outer circumferential surface of the fixed shaft, and a flow path communicating with the notch portion is provided on the fixed shaft, and a plurality of channels are provided from the teeth of the worm to the inner circumferential surface that can communicate with the notch portion. A hydrostatic bearing type worm rack featuring a distribution flow path.